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If X and Y are prime integers , what is X + Y ?

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Source: — Data Sufficiency |
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by apuso » Sun Jan 24, 2010 9:16 am
looking at option a) X-Y is a prime integer
it gives multiple sets of values for x & y which satisfy the above condition, ex: x=5, y=2 or x=7,y=5 or x=5, y=3 etc, thus this is NOT SUFFICIENT

looking at option b)Y<X<6
this also gives multiple sets of true values, ex: x=5, y=2 or x=5, y=3, thus this is NOT SUFFICIENT too

so ans is E
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by papgust » Sun Jan 24, 2010 8:51 pm
This can be solved by just plugging in simple numbers.

X+Y?

A. X-Y is a prime integer

5-2 = 3 (Prime). 5+2 = 7
7-5 = 2 (Prime). 7+5 = 12

Two or more different answers. Insufficient.

B. Y<X<6

Y and X could be any of 2,3, or 5.
If X=5, Y=2, then 5+2 = 7
If X=5, Y=3, then 5+3 = 8

Two different answers. Insufficient.

Combined,
Clearly insufficient from numbers tried in A and B.
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by bhumika.k.shah » Sun Jan 24, 2010 10:27 pm
I agree. its E
but had the second statement said that Y<X<6 and X and Y are both odd...the answer option would have been C right ?

I think it would be B as the only two prime #s less than 6 that are odd are 3 and 5

So then IMO B would be sufficient - am i right??
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by linkinpark » Mon Jan 25, 2010 7:56 am
bhumika.k.shah wrote:I agree. its E
but had the second statement said that Y<X<6 and X and Y are both odd...the answer option would have been C right ?

I think it would be B as the only two prime #s less than 6 that are odd are 3 and 5

So then IMO B would be sufficient - am i right??
2 is also a prime
530->480->580
when posting a question don't post OA(even masked) before some discussion.
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by bhumika.k.shah » Mon Jan 25, 2010 8:57 am
yes linkinpark
2 is also prime . but had the same question been asked with the 2nd statement modified to Y<X<6 and X and Y are both odd... then all i wanna know is whether B alone would be sufficient ?

in this case 2 is a prime # but not an even prime #

Thanks! :D
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by linkinpark » Mon Jan 25, 2010 9:00 am
if x and y were mentioned to be odd integers in B then yes B would have been sufficient definitely. sorry didn't read first clearly.
530->480->580
when posting a question don't post OA(even masked) before some discussion.
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by bhumika.k.shah » Mon Jan 25, 2010 9:10 am
its cool :)
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